/*

<This Java Class is part of the jMusic API version 1.5, March 2004.>

Copyright (C) 2000 Andrew Sorensen & Andrew Brown

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or any
later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

package jm.audio.synth;

import jm.audio.AOException;
import jm.audio.AudioObject;

import java.util.Vector;

/**
 * The <bl>Delay</bl> Audio Object is a simple delay line.
 * It calculates the delay time in samples (so the time will depend
 * on the current sample rate). It only passes on the delayed data
 * so an add Audio Object needs to be used in the chain to mix the
 * delayed signal with the original if that is required for an echo effect.
 *
 * @author Andrew Brown
 * @version 1.0, Sun Feb 25 18:42:45  2001
 */

public final class Delay extends AudioObject {
    //----------------------------------------------
    // Attributes 
    //----------------------------------------------
    /**
     * A place to keep the previous sample values
     */
    Vector storedSamples = new Vector();
    // Vector <Float> storedSamples = new Vector<Float>(); // solves java generics warnings but breaks 1.3 compatability
    /**
     * The number of samples long the delay line is
     */
    int sampleDelay = 0;
    /**
     * The number of samples processed so far
     */
    int sampleCounter = 0;


    //----------------------------------------------
    // Constructors 
    //----------------------------------------------

    /**
     * The Delay constructor takes the object previous
     * to it in the chain, and the delay length in samples.
     *
     * @param sampleDelay the lenght of the delay in samples
     * @param ao          the single AudioObject taken as input.
     */
    public Delay(AudioObject ao, int sampleDelay) {
        super(ao, "[Delay]");
        this.sampleDelay = sampleDelay;
    }


    //----------------------------------------------
    // Public Methods
    //----------------------------------------------


    //----------------------------------------------
    // Protected Methods
    //----------------------------------------------

    /**
     * The nextWork method for <bl>Delay<bl> will store
     * the sample and send out the delayed one instead.
     */
    public int work(float[] buffer) throws AOException {
        int returned = this.previous[0].nextWork(buffer);
        if (sampleCounter >= sampleDelay) {
            for (int i = 0; i < returned; i++) {
                // keep the current sample from the chain
                storedSamples.addElement(new Float(buffer[i]));
                // replace it with a stored sample
                Float tempFloat = (Float) storedSamples.elementAt(storedSamples.size() - 1);
                buffer[i] = tempFloat.floatValue();
                // remove the used stored sample
                storedSamples.removeElementAt(storedSamples.size() - 1);
            }

        } else { // early on pad with silence
            for (int i = 0; i < returned; i++) {
                // keep the current sample from the chain
                storedSamples.addElement(new Float(buffer[i]));
                // send out a zero value
                buffer[i] = (float) 0.0;
            }
        }

        sampleCounter++;
        return returned;
    }
}
